Speaker
Description
18+2'
We present the first comprehensive Bayesian calibration of a state-of-the-art hybrid heavy-ion collision model incorporating a novel observable: the scaled particle spectra of pions. This observable isolates the intrinsic spectral shape and reveals a remarkable degree of universality across centrality classes and collision systems. Leveraging the JETSCAPE framework, we construct Gaussian process emulators to efficiently explore the scaled spectra throughout the QGP transport parameter space.
We perform a model-to-data calibration using ALICE measurements from Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}} = 2.76$ TeV and Xe-Xe collisions at $\sqrt{s_{\mathrm{NN}}} = 5.44$ TeV. By comparing posterior distributions, we demonstrate that this differential universal observable provides complementary constraints to traditional $p_T$-integrated observables, revealing previously hidden tensions in the parameter space. Our analysis quantifies the enhanced sensitivity of scaled spectra to specific transport properties and highlights the importance of incorporating differential information in multi-observable Bayesian frameworks.
These findings establish scaled spectra as a powerful tool for precision extraction of QGP properties and pave the way for more discriminating tests of heavy-ion collision models across different collision systems and energies.